Heater



Feb. 15, 1944. P. F. HELMICK HEATER Filed Feb. 19! 1942 Patented Feb.15, 1944 HEATER Paul F. Helmiok,

Osborn,

Application February 19, 1942, Serial No. 431,539

(Granted under the act o! March 3, 1883, as

amended April 30, 1928; 370 0. G. 757) 1 Claim.

The invention described herein may be manufactured and used by or forGovernment for governmental purposes, without the payment to me oi' anyroyalty thereon.

This invention relates to a heater and more particularly to a heater ofthe type which utilizes the heat of the exhaust gases of an internalcombustion engine for heating the air contained within A the body orcabin of an automotive vehicle.

A heater of one type or another for heating the air contained within thepassenger compartment of a vehicle is essential for those vehicles whichare intended to operate in cold weather or at extremely high altitudes,and such a heater generally employs water or steam as a heat-transfermedium for conveying the heat from the internal combustion engine to thevehicle space to be heated. These water and steam-heating systems sufferfrom the disadvantage that the Water contained therein will freeze whenthe vehicle is standing idle unless precautionary measures are taken toprevent it. These systems also suffer from the disadvantage of theirconsiderable weight which is very undesirable in an aircraftinstallation.

Heating systems which utilize the heat of the exhaust gases directly forheating the air within the cabin or body of the vehicle have manyadvantages over the vapor and water heating systems but these advantagesare negatived by the fact that carbon monoxide from the exhaust gases islikely to escape into the vehicle inclosure and thereby gravely endangerthe lives of the occupants. Such hot-air heating systems, thoughformerly employed in large numbers in the automobile ileld, havepractically disappeared in recent years due to the ever present dangerof carbon monoxide poisoning, and this has come about in spite of theirinherent advantage of simplicity of construction and reliability inoperation.

The present invention is concerned with an improvement which will rendersafe even the very simplest type of exhaust manifold heater, namely onein which the air within the vehicle space to be heated is circulatedthrough a jacket circumjacent to the exhaust manifold of an internaicombustion engine. According to my invention provision is made forpositively preventing any of the exhaust gases from ndng their way intothe interior of the cabin or body as the result of a leak occurring inthe jacket or in the exhaust manifold. This is accomplished by providingan intermediate jacket lying between the exhaust manifold and theconduit through which the air to be heated is conveyed, the space withinthis intermediate jacket being lled with a heattransfer medium whosepressure is maintained at all times in excess of that obtaining in theexhaust manifold adjacent to the heater. Thus, should any leak occur inthe Jacket or in the United States Army,

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exhaust manifold, as the case may be, the heattransfer medium will flowinto the manifold and prevent any reverse ow of the exhaust gases. Thusit will be impossible for any of the noxious gases present in theexhaust manifold to nd their way into the air flowing through thehot-air conduit.

Accordingly, one of the objects of my invention is to provide anexhaust-manifold type of heater in which the escape of the exhaust gasesinto the air stream passing through the heater is positively prevented.

Another object of my invention is the provision of a heater of theexhaust-manifold type in which a heat-transfer medium contained in anintermediate jacket of the heater is maintained at a pressure exceedingthat of the gases contained within the manifold adjacent to the heater.

A furtherl object of my invention is the provision of a heater of theexhaust-manifold type in which the heat-transfer medium may becirculated through the intermediate jacket when the heater is not inuse. In lthis way, the unused heat of the exhaust gases is dissipatedand the overheating of the heater walls is prevented.

A preferred embodiment of the present invention will be hereinafterdescribed .with reference to the accompanying drawing, given merely byway of example, in which:

Figure 1 is a diagrammatic view illustrating a heater constructed inaccordance with my invention as it appears when installed on an aircraftor other vehicle. vThe heater is shown in cross section so as to clearlyillustrate the internal construction of same.

Figure 2 is a cross-sectional view of the heater taken on the line 2-2of Figure 1.

in Figure l, my improved form of heater is designated generally at lliwhile the location of one of the walls of the vehicle inclosure isindicated at l2. The heater proper is comprised of an outer casing Itwhich is connected to the exhaust pipe i6 of an internal combustionengine by means of a suitable gland nut I8. The left-hand end of thecasing is curved downwardly and is open to the atmosphere as at 2B. Thusthe exhaust gases from the engine may pass out to the' atmosphere by Wayof the exhaust pipe i6 and the casing M. Situated Within the casing I4is an intermediate tube or jacket 22 which is enlarged at its right-handend 24 so as to form an air scoop situated in the air stream flowingpast the vehicle. The left-hand end of the jacket 22 is curved upwardlyso as to pass through the wall of the casing I4, and is provided at itsextremity with a butterfly valve 28 which may be manipulated by means ofthe lever 30 so as to tightly close this end of the jacket. Aconstriction 26 provided near the mouth of the jacket 22 aids inbuilding up an air pressure within the jacket 22. Within the jacket islocated a piece of uted tubing 32 which serves as a heating chamber forthe air which is passed through the heater. To the right-hand end oftube 32 is attached a short tube 34 which is provided at its outer endwith a bell-shaped mouth 36 serving as an air scoop to force air throughthe tube 32. Communicatively connected with the tube 34 is an air inlettube 38 which. at its other end is connected to the outlet side of apositive pressure blower 40 located within the vehicle space to beheated. The left-hand end of the uted tube 32 is connected to a tube 42which passes upwardly through the wall of the jacket 22. At its upperend, the tube 42 is connected to one ofthe ports of a three-way plugvalve 44, a second port of which is connected by means of a short tube46 to a header 50 located within the cabin or body of the aircraft. Fromthis header extend the tubes 52 and 54 which convey the hot air toregisters 56 and 58 which then distribute the air to the interior of thevehicle body or cabin. A third port of the three-Way valve 44 hasattached thereto a short tube 48 which communicates at its outer endwith the atmosphere. A buttery valve 60 is provided in the vicinity ofthe mouth 36 of the tube 34 for the purpose of regulating the amount offresh air which may be admitted into the heating chamber 32.

The operation oi my device is as follows:

'I'he blower 40 draws air outof the vehicle space to be heated andforces this air through the tubes 38 and 34 to the heating chamber 32where the air is heated. The air then proceeds through the tube 42 andthe valve 44 to the header 50 after which it passes out through theregisters 56 and 58 located within the space to be heated. If it isdesired that a certain amount of fresh air be added to that withdrawnfrom the cabin the butterfly valve 60 is opened so as to permit the airpicked up by the air scoop 36 -to be forced into the heating chamber 32along with that delivered by the blower 40. If it is desired that onlyfresh air be supplied in a heated condition to the interior of thecabin, the blower 40 may be turned off and the butterfly valve 60 openedwhereby the air entering the scoop36 may pass through the heatingchamber 32 and into the cabin through the registers 56 and 58.

In case it is desired to discontinue the use of the heater entirely thevalve 44 may be manipulated to close oi` the upper end of the tube 42 soas to stop the flow of air through the heater. At the same time thebutterfly valve 28 may be opened so as to permit a ow of air through thejacket 22. This circulation of cool air through the jacket serves tocarry oi the heat from the exhaust gases and so keep the walls of thejacket cool and prevent their burning out while the heater is not inuse.

An alternative means for preventing the overheating of the walls whenthe heater is not needcd for heating the air in the cabin is provided bythe port 48 of the three-way valve 44. By opening the butterfly valve 60and turning the plug of the valve 44 through 90 degrees in a clockwisedirection from the position shown in Figure 1, a supply of cool air fromthe outside atmosphere will be caused to flow through the heatingchamber 32 and back out to the atmosmosphere instead of being led intothe vehicle space to be heated.

It will be seen that by maintaining a pressure within the jacket 22 bymeans of the scoop 24 and the constriction 26, which pressure is greaterthan that of the exhaust gases passing through the casing I4, anypossibility of the noxious gases from the exhaust leaking into theheated air is effectively prevented. In case a leak should occur in thejacket 22 at the same time that a leak exists in the Iiuted tube 32, theair contained under pressure within the jacket 22 will force its waythrough the leak in the wall of 22 and thus prevent any of the exhaustgases from entering the jacket.

It will be observed that the air contained within the jacket 22 servesas a medium for transferring the heat from the exhaust gases to thewalls of the fluted tube 32. By maintaining this air under pressure itsheat conducting properties are enhanced and an effective transfer ofheat is made possible.

It will be seen from the above that I have devised an improvedexhaust-manifold heater in which the danger of injury to the occupantsof the cabin or body of the vehicle from carbon monoxide poisoning isentirely eliminated. Due to its simplicity and light weight my improvedform of heater is ideally suited for use on aircraft where thesefeatures are of paramount importance.

The specific form of heater which I have shown in the drawing anddescribed above is merely illustrative of one possible form which myinvention might take and it is not to be construed as the only possiblemanner of constructing the same. It is obvious that various changes maybe made therein without departing from the spirit of the invention asdefined in the appended claim.

I claim:

A hot air heater of the type utilizing the exhaust gases passing throughthe exhaust mani` j. fold of an internal combustion engine as a sourceof heat, said heater comprising three tubes of diierent diametersarranged one within the other so as to form an intermediate chamber andtwo adjoining chambers, means for passing the exhaust gases through oneof said adjoining chambers, means for passing the air to be heatedthrough the other of said adjoining chambers, means located at one endof said intermediate chamber for supplying air thereto at a pressureexceeding that of the exhaust gases contained inside said one adjoiningchamber, and means located at the other end of said intermediate chamberfor enabling this end of the chamber to be selectively opened or closedto the outside l atmosphere, said other end being opened to theatmosphere when the heater is not in use so as to enable a continuousstream of air to pass therethrough, and .being closed to the atmospherewhen said heater is in use so as to cause the air to remain in asubstantially static condition within said chamber and thus serve as aneffective heattransfer medium between the hot exhaust gases and the airto be heated.

PAUL F. HELMICK.

